Electro-cautery catheter

ABSTRACT

An integrated catheter assembly for enabling diverse endoscopic in situ therapies. The assembly includes a catheter with an irrigation fluid lumen, a distal electrode tip portion that acts as a hemostat, and a cutting wire for making incisions in or ablating tissue. A cutting wire hub provides a sealing entrance for a cutting wire. An operator enables the physician to displace the cutting wire between extended and retracted positions. The cutting wire and electrode are electrically isolated. In addition, the catheter assembly may include a planar tip which, when extended outside the distal end of the assembly, assumes a substantially flat unbiased configuration for use. The apparatus of the present invention allows the physician to make incisions in or ablate tissue using electrosurgery, irrigate tissue, and cauterize or coagulate tissue without having to remove the apparatus from the working channel of the endoscope.

FIELD OF THE INVENTION

[0001] This invention generally relates to electro-surgery,electro-cauterization and electro-coagulation of tissue in the body incombination with other forms of therapy using catheters. Specifically,this invention relates to an apparatus for performing electrosurgery,electrocauterization and electrocoagulation of tissue through a workingchannel of an endoscope.

BACKGROUND OF THE INVENTION

[0002] Numerous medical procedures involve making an incision in bodytissue and controlling any consequent bleeding. When performing theseprocedures, it is very important to minimize both tissue trauma duringincision and the time required to stop internal bleeding. Minimallyinvasive or least invasive surgical techniques, such as laparoscopicendoscopic, or arthoroscopic techniques, are often used because bodytissue is usually traumatized less by those techniques than by moreinvasive conventional techniques. Electrosurgical methodologies, oftenused in conjunction with the minimally or least invasive techniques,allow the making of an incision and the stopping or stemming of bleedingwith less attendant tissue trauma and greater control than doconventional modalities.

[0003] A physician has several medical instruments in his or herarmamentarium for making an incision and stemming consequent bleeding.In accordance with one modality that is particularly suited forapplication in the gastrointestinal tract, a physician initiallypositions a flexible endoscope in the patient with its distal endproximate to an incision site, and inserts a device for making anincision through a working channel of the endoscope to the incisionsite. The physician can also insert an irrigator through a workingchannel in the endoscope to clear the area by administering water orsaline solution as a precursor to any attempts to make an incision orstop bleeding.

[0004] If the instrument being used for irrigation is like the GoldProbe™ hemostat manufactured by Boston Scientific Corporation, theassignee of this invention, the physician can then cauterize a bleedingvessel using a distally positioned hemostat. Such instruments areconstructed to be employed through a working channel of an endoscope toseal potential bleeding sites as in the gastrointestinal tract.Alternatively, the physician can retract the irrigating catheter andinsert an elongated needle through the endoscope to inject avaso-constrictor into the vessel to slow hemorrhaging. Then thephysician can remove the elongated needle and reinsert the hemostat tofinish the operation.

[0005] Some hemostats use mono-electropolar electrodes in which oneelectrode is carried by a catheter to a site while the other electrodeis an exterior ground plate placed in or on a patient. Theabove-mentioned Gold ProbeTM hemostat is an example of a device thatsupplies a suitable current density and wave form of radio frequencyenergy to perform electro-coagulation or electro-cauterization. Itutilizes a catheter with a bipolar electrode assembly located on aflexible shaft formed of a ceramic cylinder having a hemispherical end.The ceramic tip includes a pair of spaced gold spiral electrodes appliedto its cylindrical surface and domed end. RF energy applied to theelectrodes produces a current through adjacent tissue that heats andcauterizes the hemorrhaging vessel which is contacted by the tip of thecatheter.

[0006] Physicians often use different catheters to perform differentfunctions. For example, physicians will often use one catheter to makean incision and another to perform hemostasis and irrigation. Theexchange of catheters to provide different functions extends the time tocomplete therapy, increases the risk to the patient and also increasespatient discomfort. Consequently, physicians have to weigh the time,complexity and benefits of interchanging single or dual purposecatheters to change treatment modalities against whatever disadvantagemay result by working with a single catheter.

[0007] U.S. Pat. No. 5,336,222, the contents of which are incorporatedherein, discloses an integrated catheter assembly for enabling diversein situ therapies which includes a catheter with an irrigation fluidlumen, a distal tip portion that acts as a hemostat and a needle forinjection therapy.

SUMMARY OF THE INVENTION

[0008] In accordance with this invention, an integrated catheterassembly that enables a physician to utilize diverse in situ therapymodalities at selected tissue sites includes a catheter, an electrodetip and an electrode cutting wire. A lumen extends from a proximal endto a distal end of the catheter structure to provide a passage from alocation externally of the patient to the tissue being treated. Thebipolar electrode structure attaches to the distal end of the catheterstructure and provides hemostatic therapy to selected tissue.

[0009] The electrode structure additionally has a central lumen alignedwith the catheter lumen for enabling the transfer of irrigation fluidsto tissue being treated. The cutting wire structure is electricallyisolated from the electrode tip and extends from a proximal endexternally of the patient through the lumens in the catheter and theelectrode structure for axially displacement relative to the catheterand electrode structures. The cutting wire can be extended distallybeyond and can be retracted proximally of a distal end surface of theelectrode tip.

[0010] In an exemplary embodiment of a catheter assembly according tothe present invention, a distal end of the cutting wire includes asubstantially planar tip. The planar tip may be formed to achieve both aretracted, substantially circular configuration for insertion through anendoscope and for insertion of the endoscope through a lumen, and anextended, substantially planar configuration for use. The planar tip mayfurther include bipolar circuitry on at least one face.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The various objects, advantages and novel features of thisinvention will be more fully apparent from a reading of the followingdetailed description in conjunction with the accompanying drawings inwhich like reference numerals refer to like parts, and in which:

[0012]FIG. 1 is a perspective view of an integrated catheter assemblyaccording to the present invention.

[0013]FIG. 2 is a side view, partially in section, of the integratedcatheter assembly shown in FIG. 1, which assembly extends betweenproximal and distal end portions and includes a catheter, a cutting wireand a bipolar electrode assembly.

[0014]FIG. 3 is a side view, partially in section, showing in detail thedistal end portion of the apparatus in FIG. 2 including the bipolarelectrode assembly in which the cutting wire is retracted.

[0015]FIG. 4 is a side view, partially in section, showing in detail thedistal end portion of the apparatus in FIG. 2 in which the cutting wireis extended.

[0016]FIG. 5 depicts a preferred tip structure that can be substitutedfor the bipolar electrode assembly shown in FIGS. 3 and 4.

[0017]FIG. 6 is a side view of a cutting wire assembly used in thestructure shown in FIGS. 2 through 4.

[0018]FIG. 7 is a side view of an alternate embodiment of a cutting wireassembly.

[0019]FIG. 8A is a perspective view of an exemplary integrated catheterassembly having a planar tip according to the present invention, theplanar tip being in a retracted position.

[0020]FIG. 8B is an expanded perspective view of the planar tip of 8A.

[0021]FIG. 9A is a perspective view of the assembly of FIG. 8A, with theplanar tip of 8A in an extended position.

[0022]FIG. 9B is an expanded perspective view of the planar tip of 9A.

[0023]FIG. 10 is a perspective view of an exemplary planar tip accordingto the present invention.

[0024]FIG. 11 is a perspective view of a further exemplary planer tipaccording to the present invention.

[0025]FIG. 12 is another perspective view of the planar tip of FIG. 11.

DETAILED DESCRIPTION OF THE INVENTION

[0026]FIG. 1 shows the preferred embodiment of a electro-surgery andintervention apparatus according to the present invention, whichincludes a catheter assembly 10, a bipolar electrode tip 20, anelectrode cutting wire 23, an operator 24, an electrical cutting wireconnector 70, bipolar electrode tip connectors 2 and 4, and anirrigation hub 6.

[0027]FIG. 2 discloses the integrated catheter assembly 10 that enablesa physician to utilize diverse in situ therapy modalities at selectedtissue sites without withdrawing the assembly 10 from the workingchannel or lumen of an endoscope. It includes a modified bipolarhemostat and irrigation system 11, such as the above identified GoldProbe™ hemostat and that described in U.S. Pat. No. 5,403,311(incorporated herein by reference for its teachings). The system 11enables a physician to utilize a multipurpose device for making anincision in tissue using electrosurgery, as well as for performingbipolar hemostasis and irrigation in the treatment of a bleeding vessel.The system 11 particularly includes a catheter 12 with a single lumenthat extends from a distal location 13 to a proximal location 14. At theproximal location 14 a catheter hub 15 carries the catheter 12 from aLeur lock or similar catheter fitting 16 toward the distal location 13.Electrical leads 17 from an RF generator connector 18 also enter thecatheter hub 15. RF generators of the type utilized with this apparatusare well known and therefore not shown. The connector 18 may be onewhich connects using banana type plugs. The electrical leads 17 are ledinto the center of the catheter 12 in the hub 15 thereby to be carriedthrough a central lumen 19 of the catheter 12 to the distal location 13and a bipolar electrode assembly 20. As an alternative, the catheter 12may incorporate electrical leads in the catheter wall thereby toeliminate any contact between irrigating solutions in the lumen 19 andthe electrical leads 17. The bipolar electrode assembly 20 whenenergized over the electrical leads 17 provides hemostatic therapy.

[0028] In accordance with this invention, a wire hub 21 directs thecatheter 12 therethrough and supports the proximal end of a wireassembly 22 that includes an electrode cutting wire 23. The cutting wire23 can move between extended and retracted positions by manipulation ofan operator 24. The operator 24 is shown at its extended position inFIG. 2 by the solid lines and in its retracted position by phantomoperator 24′. When the cutting wire 23 extends distally beyond thedistal end of the bipolar electrode assembly 20 as shown in FIGS. 2 and4, it can contact and penetrate tissue, enabling a physician to makesurgical incisions into tissue or ablate tissue.

[0029] Referring now to different sections of the apparatus shown inFIG. 2 in more detail, FIGS. 3 and 4 depict a distal end location 13 ofthe integrated catheter assembly 10. In each of FIGS. 3 and 4 the distalend of the catheter 12 terminates at the bipolar electrode assembly 20.Although the electrode assembly 20 is described as bipolar, it is wellunderstood in the art that an electrode assembly, such as the electrodeassembly 20 here, can also be monopolar. The monopolar form of theelectrode assembly 20 has only one of the spiral electrodes (i.e. 29A or29B).

[0030] More specifically the bipolar electrode assembly 20 includes acylindrical body portion 26 having a hemispherical distal end tip 27 anda proximally extending shank 28 at its other end. Discrete spiralelectrodes 29A and 29B are disposed on the outer surface of the bodyportion 26 and the end tip 27 and connect to the electrical leads 17. Adistal tip lumen 30 extends through the body portion end tip 27 andshank 28. The shank 28 is nested and supported by the catheter 12.

[0031] Still referring to FIGS. 3 and 4, a cutting wire guide portion 31includes an end section 32 that is located in the proximal end of thelumen 30 and coextensive with a portion of the shank 28. The guide wire31 can be, for example, located within a centerbore at the proximal endof the tip 27, or , as shown in FIGS. 3 and 4, within the lumen 30. Thecutting wire guide portion 31 extends proximally from the shank 28 andconstitutes a pervious guide tube for the cutting wire 23. Morespecifically, the cutting wire guide 31 is formed as a spring withmultiple spaced turns that define inter-turn passages 33. These passages33 allow fluid to transfer from the catheter lumen 19 and through thedistal tip lumen 30 to exit from the end tip 27. Fluid flow isrelatively unimpeded in the structure shown in FIG. 3 when the cuttingwire 23 is retracted. The extension of the cutting wire 23 to theposition shown in FIG. 4 restricts the distal tip lumen 30, but flow canstill occur.

[0032]FIG. 5 depicts a preferred embodiment for the bipolar electrodeassembly 20. In this particular embodiment, a tube 34 replaces thespring 31. The tube 34 has a section 35 that fits in the lumen 30 and iscoextensive with a portion of the shank 28 and another section 36 thatis proximal of the shank 28. This second section 36 includes a pluralityof radially extending apertures 37 that act as passages for irrigationfluids from the catheter 12 through a central lumen 38.

[0033] Each of FIGS. 3 through 5 depict alternative embodiments of abipolar electrode assembly 20 that includes first and second electrodes29A and 29B for providing hemostatic therapy. In each embodiment a bodyportion 26 has a hemispherical distal end 27 and carries the electrodes29A and 29B. A shank 28 extends proximally of the body portion 26 forinsertion into the lumen 19 at the distal end of the catheter 12. Atubular pervious cutting wire guide 31 extends proximally from the shankportion 28 in the lumen 19 to be coextensive with the distal portion ofthe catheter 12 for supporting the distal end of the cutting wire 23particularly in its retracted position.

[0034] Referring to FIG. 2, the operator 24 associated with the cuttingwire assembly 22 includes a proximal end fitting 40 that can connect toa cutting wire electrical connector 70 (shown in FIG. 1) which enablesthe cutting wire 23 to be electrically charged. At its opposite end, theoperator 24 includes a collar 41 and set screw 42 or other attachingapparatus for affixing the operator 24 to the cutting wire 23. Suchapparatus is known in the art. In this particular embodiment theoperator 24 and cutting wire 23 lie along an axis 43.

[0035] The cutting wire hub 21 can be molded or otherwise formed toinclude a proximal compartment 44 defined by side walls 45 and 46 andend walls 47 and 48. An aperture 50 through the end wall 48 accommodatesthe operator 24 while an aperture 51 at the distal end wall 47accommodates the cutting wire 23. The end walls 47 and 48 support theproximal end of the cutting wire assembly 22 and limit the range oftravel of the operator 24 along the axis 43 between the position shownin FIG. 2 wherein the collar 41 abuts the wall 47 and a retractedposition in which the collar 41 abuts the end wall 50.

[0036] An intermediate compartment 52 disposed distally of the proximalcompartment 44 supports the catheter 12 in a radiused orientation.Curved and straight side walls 53 and 54 of the cutting wire hub 21 andtransverse end walls 55 and 56 define the compartment. The end wall 55extends between the side wall 53 and 54; the end wall 56, between theside wall 53 and the intersection of the side wall 45 and end 47.Apertures 57 and 58 in the end walls 55 and 56 respectively capture thecatheter 12.

[0037] An elastomeric seal 60 surrounds the catheter 12 and is locatedin the intermediate compartment 52. The cutting wire 23 penetrates theseal 60 and the wall of the catheter 12 thereby to be located in thecatheter lumen 19 to extend through the distal tip 30 as shown in FIG.3. The seal 60 prevents leakage from the catheter 12 even during axialdisplacement of the cutting wire 23 along the axis 43. This seal 60generally will be formed of an elastomeric material and can take any ofseveral forms as known in the art.

[0038] The cutting wire hub 21 includes another proximal compartment 61adjacent the proximal compartment 44. The compartment 61 is formed by aproximal end wall 62, the side walls 45 and 53 and the end wall 57. Theend walls 57 and 62 in this compartment 61 support the catheter 12proximally of the seal 60 and, with the compartment 52 and end wall 55,provides an angular offset to the catheter 12 with respect to the axis43.

[0039] A distal compartment 64 is formed by the side walls 53 and 54,the end wall 55 and a distal end wall 65. An aperture 66 in the end wall65 holds the catheter 12. The end walls 55 and 65 thereby maintain thealignment of the catheter 12 along the axis 43 to facilitate theplacement and containment of the cutting wire 23 within the catheter 12lumen 19 distally of the cutting wire hub 21.

[0040] Still referring to FIG. 2, it is desirable to manufacture thecutting wire hub 21 as a standard unit for a variety of applications. Insome applications, the limits imposed on the axial travel of the cuttingwire 23 by the end walls 47 and 48 may allow an extension of the cuttingwire 23 from the bipolar electrode assembly 20 that is greater thandesired. It is possible to customize that extension by applying apositive stop structure to the cutting wire assembly 22. One suchstructure is shown in FIGS. 3, 4 and 6 where like numbers refer to likeelements. As shown, particularly in FIG. 6, the cutting wire assembly 22includes the operator 24 with its end fitting 40 and collar 41. Thecutting wire 23 extends as a constant diameter wire to its distal end67. A collar 70 having a distal, radially extending end surface 71 islocated on an insulated portion of the cutting wire 23 at somepredetermined location spaced from the distal end 67 by a distance thatequals the length of the desired extension plus the distance between theend tip surface 27 of the bipolar electrode assembly 20 as shown in FIG.2 and a proximal end 72 of the cutting wire guide 31 as shown in FIGS. 3and 4.

[0041] Consequently as the cutting wire 23 moves from its retractedposition in FIG. 3 to its extended position in FIG. 4, the distal endsurface 71 of the collar 70, that overlies the spring 31, abuts the end72 and prevents any further distal extension of the cutting wire 23. Ifthe bipolar electrode assembly 20 of FIG. 5 were used, the end surface71 would abut an end surface 73 on the tube 34.

[0042]FIG. 7 discloses an alternative stop mechanism wherein the cuttingwire assembly 22 includes an operator 24 with proximal end connector 40and distal collar 41. In this embodiment the cutting wire assembly 22comprises a distal hollow section 74 and a proximal hollow section 75.The distal section 74 has a given diameter corresponding to the diameterof the cutting wire 23 shown in FIG. 6 and determined by the applicationrequirements. The length of the distal section 74 equals the desiredextension of the cutting wire plus the distance from the distal end tip27 to either end surface 72 of the guide 31 in FIGS. 3 and 4 or the endsurface 73 of the tube 34 in FIG. 5. The proximal section 75 extendsfrom the distal portion 74 to the operator 24 and has a larger diameter.Consequently the proximal portion 75 forms an annular radial surface 76at its distal end that also will abut either the end 72 of the guide 31in FIGS. 3 and 4 or the end 73 of the cutting wire guide tube 34 shownin FIG. 5.

[0043] The cutting wire 23 can be conductive along its entire length tothe operator 24, or it can have conductors which are attached at a pointalong the length of the wire 23 that is within the lumen of the catheter12. Additionally, all but the distal end of the cutting wire 23 can becoated or covered. Further, the wire 23 may be solid or hollow, in whichcase the lumen of the wire 23 can be used to allow passage of fluids forinjecting. The operator 24 can have a Luer type fitting which allowspassage of fluids for injecting and also have electrical leads to chargethe cutting wire 23.

[0044] When a physician needs to make an internal incision in a patient,the physician will, as in the prior art, insert an endoscope with aworking channel. The physician can then insert the integrated catheterapparatus 10 shown in FIG. 2 through the working channel, normally withthe cutting wire 23 in its retracted position (as shown in FIG. 3). Ifthere is already internal bleeding in the area and it is necessary toirrigate the area, the physician can apply irrigating fluid through theconnector 16 and the catheter lumen 19 to be ejected at the distal endtip 27 through the lumen 30 as shown in FIGS. 2 and 3. If upon viewingthe site the physician decides to utilize hemostasis, it is merelynecessary to position the bipolar electrode assembly 20 at the tissueand energize the electrodes 29A and 29B. The cutting wire assembly 22has no effect on this process. If, on the other hand, the physiciandetermines that the making an incision is appropriate before or in lieuof hemostasis, the physician can easily extend the cutting wire 23 andapply and use the cutting wire to make a surgical incision in thetissue. Thereafter the physician can irrigate the site at will and electto use hemostasis to stem or stop any bleeding. Each of these functionscan be performed without withdrawing the integrated catheter apparatus10 from the endoscope.

[0045] It will be helpful to describe some specific embodiments of thisinvention for the purpose of further understanding the construction anduse of this invention. Generally, the outer diameter of the catheter 12can be as small as 5 Fr. and as large as can be accommodated by theinner diameter of an endoscopic channel. In certain specificembodiments, for example, the catheter assembly 10 can comprise a 7 Fr.or 10 Fr. catheter 12 and a 21 gauge cutting wire 23. In an anotherembodiment, using a cutting wire as shown in FIG. 7, the distal catheterportion comprises a 23-25 gauge tubular structure while the proximalportion comprises a 21 to 22 gauge tubular structure. In addition, oneembodiment of the catheter assembly 10 in FIG. 2 extends about 220 cm.between the distal tip portion 13 and the hub 21 while the extension ofthe cutting wire 23 from the bipolar electrode assembly is limited to amaximum of 6 mm.

[0046]FIGS. 8A through 12 illustrate additional exemplary embodiments ofa catheter assembly according to the present invention, and inparticular a catheter assembly including a substantially planar tip 121.In general, the catheter assemblies illustrated in FIGS. 8A through 12may include elements and features similar to those described above, withthe addition of planar tip 121.

[0047] In an unbiased position, planar tip 121 has a substantially flatcross section, where “substantially flat” is understood to meancross-sections which are flat and cross-sections which have apredetermined curvature (as shown in FIGS. 9A and 9B). In the same way,the term “planar tip” is used herein for convenience, and generallyrefers to any relatively flat or laterally compressed surface,regardless of thickness and regardless of whether the surface defines aplane or has a predetermined curvature.

[0048] Generally, planar tip 121 is formed of any suitable material, butpreferable one that is flexible so that, as shown in FIGS. 8A and 8B,planar tip 121 may be inserted into and through a catheter 12. In thisposition, planar tip 121 has a substantially circular cross section, asshown in FIG. 8B. This arrangement allows planar tip to bend ifnecessary, to facilitate navigation to an operative position.

[0049] Once placed in an operative position, a cutting assembly whichmay include a shaft or wire 23 can be extended to place planar tip 121into an extended position clear of catheter 12. Once planar tip 121exits the distal end of catheter 12, it may assume its unbiased,substantially flat configuration illustrated in FIGS. 9A and 9B. In thisconfiguration, planar tip 121 may be used as a cutting blade, or may beused as an electrocautery device, desiccation device, or ablation device(or any suitable combination thereof), as described herein.

[0050] Preferably planar tip 121 includes an electrode, which may beformed on a face of planar tip 121 by circuitry. In the illustratedembodiment of FIG. 10, planar tip 121 includes a bipolar electrodeformed by two circuits 123 a and 123 b. Alternatively, planar tip mayinclude a monopole electrode as known in the art. When formed as abipolar electrode, circuits 123 a, 123 b may be in any suitable pattern.Preferably planar tip 121 is constructed of non-conductive materials, orincludes a face or coating of non-conductive materials, to separatecircuits 123 a, 123 b. Circuits 123 a and 123 b may be connect toelectrical conduits within catheter 12, as described above.

[0051] As also illustrated in FIG. 10, planar tip 121 preferablyincludes a tapered base 125, which may be connected to shaft or wire 23.Tapered base 125 assists planar tip 121 in “rolling” back to a retractedposition within catheter 12. In this retracted position, planar tip 121may have a generally circular cross section. It should also be notedthat while the planar tip 121 illustrated herein is generallyrectangular in shape (apart from tapered base 125), planar tip 121 maybe any suitable shape, for example circular, oval, or ovoid.

[0052]FIGS. 11 and 12 illustrate an additional exemplary embodiment of aplanar tip 121 according to the present invention. In this embodiment,planar tip 121 is fixed relative to the distal end of catheter 12,rather than movable with respect to catheter 12. In this embodiment,catheter 12 with planar tip 121 may be introduced as a unit, for examplethrough an endoscope.

[0053] Although this invention has been described in terms of a specificembodiment, and certain modifications, still other modifications can bemade. For example, cutting wire assembly 22 can comprise a one-piecemetal structure in the form shown in FIG. 6. In the form shown in FIG. 7the distal portion might be constructed of a metal while the proximalportion 75 also may include means for preventing rotation about the axis43 during use. Thus it will be apparent that these and othermodifications can be made to the disclosed apparatus without departingfrom the invention.

What is claimed is:
 1. A catheter assembly, comprising: a catheterhaving proximal and distal ends and a catheter lumen extendingtherethrough; a cutting assembly disposed at least partially within thelumen, the cutting assembly including a substantially planar tipselectively movable between retracted and extended positions, whereinwhen the planar tip is in the extended position, the planar tip has asubstantially flat cross section.
 2. The catheter assembly according toclaim 1, wherein the planar tip includes an electrode formed by acircuit disposed on a face of the planar tip.
 3. The catheter assemblyaccording to claim 2, further comprising an electrical conduit disposedat least partially within the catheter lumen and having proximal anddistal ends, wherein the distal end of the electrical conduit isconnected to the electrode and the proximal end is connected to anelectrical source.
 4. The catheter assembly according to claim 1,wherein the planar tip includes a bipolar electrode formed by firstsecond circuits disposed on a face of the planar tip, the first circuitand the second circuit being separated by a non-conductive portion ofthe planar tip.
 5. The catheter assembly according to claim 4, furthercomprising first and second electrical conduits, each disposed at leastpartially within the catheter lumen and each having proximal and distalends, wherein the distal end of the first electrical conduit isconnected to the first circuit and the proximal end of the first conduitis connected to a first electrical source, and wherein the distal end ofthe second electrical conduit is connected to the second circuit and theproximal end of the second conduit is connected to a second electricalsource.
 6. The catheter assembly according to claim 1, wherein thecutting assembly further includes a shaft maintained within the catheterlumen, the shaft having a distal end connected to the planar tip, theshaft being operable to move the planar tip between the retracted andextended positions.
 7. The catheter assembly according to claim 6,wherein the planar tip includes a tapered base, the tapered base beingconnected to the shaft.
 8. The catheter assembly according to claim 7,wherein the planar tip includes an electrode formed by a circuitdisposed on a face of the planar tip.
 9. The catheter assembly accordingto claim 8, further comprising an electrical conduit disposed at leastpartially. within the catheter lumen and having proximal and distalends, wherein the distal end of the electrical conduit is connected tothe electrode and the proximal end is connected to an electrical source.10. The catheter assembly according to claim 7, wherein the planar tipincludes a bipolar electrode formed by first second circuits disposed ona face of the planar tip, the first circuit and second circuit beingseparated by a non-conductive portion of the planar tip.
 11. Thecatheter assembly according to claim 10, further comprising first andsecond electrical conduits, each disposed at least partially within thecatheter lumen and each having proximal and distal ends, wherein thedistal end of the first electrical conduit is connected to the firstcircuit and the proximal end of the first conduit is connected to afirst electrical source, and wherein the distal end of the secondelectrical conduit is connected to the second circuit and the proximalend of the second conduit is connected to a second electrical source.12. The catheter assembly according to claim 11, wherein when the planartip is in the retracted position, the planar tip has a substantiallycircular cross section.
 13. The catheter assembly according to claim 12,wherein when the planar tip is in the extended position, the planar tiphas a slightly curved cross section.
 14. The catheter assembly accordingto claim 12, wherein when the planar tip is in the extended position,the planar tip has a flat cross section.
 15. The catheter assemblyaccording to claim 6, further comprising an inner sheath disposed withinthe catheter lumen, the inner sheath having a sheath lumen therethrough,wherein the cutting assembly is at least partially maintained within thesheath lumen.
 16. A planar tip for a catheter assembly, comprising: asubstantially planar surface having first and second faces; and anelectrode disposed on the first face; wherein when the planar surface isin an unbiased position, the planar surface has a substantially flatcross section.
 17. The planar tip according to claim 16, wherein whenthe planar surface is in an unbiased position, the planar surface has aslightly curved cross section.
 18. The planar tip according to claim 17,wherein the electrode is a bipolar electrode formed by first and secondcircuits disposed on the first face, the first and second circuits beingseparated by a non-conductive portion of the planar surface.
 19. Theplanar tip according to claim 16, wherein when the planar surface is inan unbiased position, the planar surface has a flat cross section. 20.The planar tip according to claim 19, wherein the electrode is a bipolarelectrode formed by first and second circuits disposed on the firstface, the first and second circuits being separated by a non-conductiveportion of the planar surface.
 21. A catheter assembly, comprising: acatheter having proximal and distal ends; and a cutting assemblydisposed at the distal end of the catheter, the cutting assemblyincluding a substantially planar tip; wherein the planar tip includes anelectrode formed by a circuit disposed on a face of the planar tip. 22.The catheter assembly according to claim 21, further comprising anelectrical conduit disposed at least partially within the catheter andhaving proximal and distal ends, wherein the distal end of theelectrical conduit is connected to the electrode and the proximal end isconnected to an electrical source.
 23. The catheter assembly accordingto claim 21, wherein the electrode is a bipolar electrode formed byfirst second circuits disposed on a face of the planar tip, the firstcircuit and the second circuit being separated by a non-conductiveportion of the planar tip.
 24. The catheter assembly according to claim23, further comprising first and second electrical conduits, eachdisposed at least partially within the catheter and each having proximaland distal ends, wherein the distal end of the first electrical conduitis connected to the first circuit and the proximal end of the firstconduit is connected to a first electrical source, and wherein thedistal end of the second electrical conduit is connected to the secondcircuit and the proximal end of the second conduit is connected to asecond electrical source.